U.S. Pat. No. 4,355,962 discloses a pump that includes a pushbutton which is movable relative to a pump body between a low position and a high position and which co-operates therewith to define a pump chamber of variable volume, which chamber communicates with a dispensing orifice via a delivery valve which includes a ball that constitutes a retaining valve member in a housing of the pushbutton.
Such a pump comprises a relatively large number of parts and manufacture thereof is expensive.
There exists a need to have a pump whose manufacturing cost is lower, but without the reduction in cost being made to the detriment of reliability.